At present, the standard for heating a mobile residence, including recreational vehicles, busses, vans, travel trailers, fifth wheelers, mobile homes, aircraft, watercraft, and the like, has been to use liquefied petroleum gas (LPG) as a single, primary heat source. As would be understood by those skilled in the Art, LPG is a flammable mixture of hydrocarbon gases commonly used as a fuel in heating certain appliances (e.g., a gas water heater or a gas stove) and confined areas within a mobile residence. Common varieties of LPG may include mixes that are primarily propane or butane based. These fuel sources can consist of solely butane or solely propane, or more commonly, mixes having both propane (C3H8) and butane (C4H10), depending on the season and the particular vendor of the LPG mix. As would be understood by those skilled in the Art, in the winter months, more propane may be in the mix, and in summer months, more butane may be in the mix.
Although LPG is a low carbon-emitting hydrocarbon fuel that is commonly used to heat mobile residences, there are numerous drawbacks associated with using heat sources operating on this fuel type, as opposed to utilizing other heaters that run on electricity. For example, the cost of LPG is often significantly more expensive than other available heat sources, particularly when an electric power source is readily available as an alternative energy source (e.g., when a shore power source is publically available at an RV park); LPG is flammable and it needs to be properly stored in special tanks that prevent the possibility of a fire or an explosion (i.e., in the event an accident would ignite the LPG within the tank); LPG fuel use results in a toxic carbon monoxide byproduct that can endanger persons residing within a mobile residence if a gas furnace's exhaust fumes were to leak into the confined living area(s) of the mobile residence (e.g., within the cabin of an RV); LPG heating systems require pipes to transfer the gas, and the igniter mechanism of gas furnaces are susceptible to failure due to igniter jets becoming clogged with dust, debris, or spider webs; the tanks this fuel is stored in generally need to be refilled on a semi-regular basis so they do not run out of LPG at inopportune times; and the locations for refueling LPG tanks might not be readily available in certain remote geographic locations where the gas furnaces of mobile residences are routinely utilized.
Further, when using LPG as fuel for a gas furnace that is providing heat to a confined area within a mobile residence, it is not uncommon to have temperatures in that area become too hot or too cold during the operation of the gas heating system. This is so, because furnace based heating and ventilation systems generally operate at very high temperatures and most temperature regulation means (e.g., thermostat devices capable of sensing and adjusting room temperature) often fail to adequately compensate for dramatic temperature changes in a timely manner. Also, because these gas furnace systems run so hot, it generally takes longer for temperatures to cool down in the confined area being heated. This is due to the fact that the heating and ventilation system itself can take a while to cool down.
A corresponding residual heating effect can occur shortly after a gas furnace is turned off, as the system attempts to balance its surface temperatures with a desired room temperature (i.e., the temperature within the confined area of the mobile residence) by radiating retained heat that is essentially remaining thermal energy residing within the metal furnace and ventilation system components and housings. This residual heating effect can negatively impact the temperature control system of a mobile residence and it can also be a source of wasted energy, particularly if a resident air-conditioning system is automatically initiated to combat the unwanted residual heating effects, such as when a preferred temperature, which is lower than a current room temperature, is selected via a resident thermostat device.
Accordingly, although LPG is a viable, relatively clean-burning fuel that is commonly used for heating many mobile residences today, there remains a need to facilitate switching over to a functionally equivalent electric heat source having adequate, distributed heat output capability for a particular mobile residence, whenever feasible. Modern portable electric space heaters generally do not offer adequate, distributed heat output or capacity to properly heat an entire mobile residence. These spot heaters typically have a relatively low power rating and they are not able to be paired with the existing ventilation system of a mobile residence in order to properly facilitate distributing heat to multiple confined areas within a mobile residence or to adequately distribute heat to different portions of the same larger confined area. Further, these portable space heaters can cause a fire hazard when left unattended, due to their feeble construction (e.g., due to their plastic housings and low quality power electronics and wiring) and the fact that they are not configured to be secured within a designated fireproof area or housing within a mobile residence.
Accordingly, it would be beneficial to have improved systems and methods for heating confined areas that could take advantage of a safe efficient electric heat source alternative. It would be desirable if these systems and methods did not solely rely on a single LPG heat source to heat a mobile residence. Further, it would be beneficial if these solutions offered flexibility to the user, such that a user could elect a preferred heat source under varying environmental conditions and in various geographic locations where resource availability might be limited; for example, where a local LPG refill location is not readily available or where an electric power supply is either not present or not accessible. Further, it would also be beneficial to have some levels of automation in these systems, such that heat source selection (between an electric heat source and a gas furnace) could be preprogrammed to facilitate logical automated selection of an appropriate heat source when both gas and electric energy supplies are available. For example, when certain default conditions are detected, heat source selection may be automatically designated by a switch or a controller's onboard logic circuitry (e.g., in an auto-detect mode).